Impact of Hurricane Harvey - Additional Information (Detail)			3 Months Ended	6 Months Ended	12 Months Ended
		Aug. 31, 2017 USD ($) Building	Dec. 31, 2017 USD ($)	Jun. 30, 2017	Dec. 31, 2017 USD ($)
Unusual Or Infrequent Item [Line Items]
Hurricane related expenses and reconstruction costs aggregate net deductible from insurance coverage		$ 25,000
Hurricane related lost income aggregate deductible from insurance coverage		100,000
Hurricane related expenses					$ 4,967,000
Proceeds in excess of the damaged property write-downs			$ 2,033,000		2,033,000
Commercial Insurance Carrier | Maximum
Unusual Or Infrequent Item [Line Items]
Property insurence coverage		50,000,000
Commercial Insurance Carrier | Maximum | Property Damage Coverage for Each Buildings
Unusual Or Infrequent Item [Line Items]
Property insurence coverage		$ 20,000,000
National Flood Insurance Program
Unusual Or Infrequent Item [Line Items]
Number of medical office buildings | Building		5
National Flood Insurance Program | Maximum | Property Damage Coverage for Each Buildings
Unusual Or Infrequent Item [Line Items]
Property insurence coverage		$ 500,000
Hurricane Harvey, Extensive Water Damage
Unusual Or Infrequent Item [Line Items]
Percentage of damaged properties from consolidated revenues				2.00%
Hurricane Harvey, Extensive Water Damage | Houston, Texas
Unusual Or Infrequent Item [Line Items]
Number of medical office buildings | Building		5
Properties Damaged and Closed from Hurricane Harvey | Spring, Texas | Cypresswood Professional Center
Unusual Or Infrequent Item [Line Items]
Number of medical office buildings | Building		2
Properties Damaged and Closed from Hurricane Harvey | Kingwood, Texas | Professional Buildings at Kings Crossing
Unusual Or Infrequent Item [Line Items]
Number of medical office buildings | Building		2
Properties Damaged and Closed from Hurricane Harvey | Kingwood, Texas | Kelsey-Seybold Clinic at Kings Crossing
Unusual Or Infrequent Item [Line Items]
Number of medical office buildings | Building		1
Hurricane Harvey
Unusual Or Infrequent Item [Line Items]
Hurricane related expenses					4,967,000
Property damage expenses	[1]				3,578,000
Remediation and demolition expenses	[2]				1,389,000
Hurricane related insurance recoveries					7,000,000
Proceeds in excess of the damaged property write-downs					2,033,000
Aggregate lost revenue for hurricane related impact			$ 510,000		$ 510,000

[1] (a.)Consists of the aggregate net book values of the estimated damaged depreciable assets at each property based upon our assessments of the real estate assets. Since the net book values of the damaged assets were not separately determinable, the write-downs were determined using a systematic and rational method to allocate the long lives asset’s carrying amounts to the affected components

[2] (b.)Consists of the aggregate remediation, demolition and general clean-up costs for the properties listed above.